I think we're seeing two conflicting trends at work. People have better and better consumables in their lives: always-connected pocket computers, cars with amazing safety systems that last much longer than before, and bigger rental apartments with amenities like air conditioning, cable TV and WiFi. At the same time, they are more and more likely to be living paycheck to paycheck with no savings, and no hope of owning their residence. The working class is simultaneously wealthier than ever before (pocket computers !) and poorer than ever before (can't afford to see a doctor !). What's undoubtedly true is that income inequality has grown dramatically in the US.
But they are not more likely to be living paycheck to paycheck. That likelihood has not increased. That is simply how most people live, and how they have AFAICT always lived.
Income is not the dominant factor in whether or not someone lives paycheck to paycheck. People live this way with startlingly high incomes.
